Ethanol perturbs a multitude of cellular functions because of its free access to all cellular compartments. The differential impact of ethanol on various tissues most likely relates to fundamental molecular differences between cells. In order to determine the concentration-dependent and temporal-dependent effect of ethanol on cellular events at the molecular level, we have been working with a well-characterized tumor cell line (AtT-20 cells) of anterior pituitary (AP) origin and dispersed AP cells, which contain multiple membrane receptors and secrete several stress hormones. Our approach is to understand the effect of ethanol on the sequences of events from membrane-receptor activation to intracellular-messenger systems to physiological responses (hormone release). Our results suggest that ethanol differentially affects certain cellular events in a dose- and duration-related manner. Incubation of AP or AtT-20 cells with ethanol for 1-4 hours has only a marginal effect on hormone release and cAMP levels. In contrast, preincubation of cultured cells with ethanol for 24 hours alters, cAMP-dependent hormone release, with only a slight effect on protein kinase C-mediated hormone release. Alteration of acute ethanol-induced membrane properties, as determined by CRF membrane binding, does not parallel the changes oberved with corticotropin-releasing factor (CRF)-induced hormone release. Finally, ethanol treatment of cultured AP and AtT-20 cells results in a substantial reduction of POMC mRNA levels, suggesting that chronic ethanol treatment reduces the transcription of the POMC gene.